The present invention relates to a pedal keyboard for an electronic musical instrument.
In an electronic musical instrument such as an electronic organ in which a key switch is opened or closed upon depression of a key in a manual keyboard to electrically generate a musical tone with a predetermined pitch corresponding to the depressed key, a musical tone output from a tone generator is also controlled by a pedal keyboard to generate a musical tone with an artistic expression. A conventional pedal keyboard is disposed at a lower portion of the front surface of the housing so as to be vertically movable. Many requirements are imposed on such a pedal keyboard: the pedal keyboard must have a simple structure, easily installed, provide smooth and sharp movement and have a good stop with little noise. Various mechanisms for the pedal keyboard have been conventionally proposed. A conventional pedal keyboard comprises foot keys vertically pivotable, springs for biasing the foot keys so as to return them to initial positions, respectively, and stoppers for limiting the pivotal movement of the foot keys. Conventional foot key arrangements are illustrated in FIGS. 1A to 1E. Throughout FIGS. 1A to 1E, reference numeral 1 denotes a pedal key; 2, a pivot 2 for the pedal key 1; 3, a spring for biasing the pedal key 1 so as to return it to the initial position; 4a, an upper limit stopper; and 4b, a lower limit stopper. In a structure shown in FIG. 1A, the upper and lower stoppers 4a and 4b are located near a front end portion (player's side) of the pedal key 1, and the spring 3 is located behind the upper and lower stoppers 4a and 4b to bias the pedal key 1 upward. The pivot 2 is located behind the spring 3 so as to support the pedal key upward. Referring to FIG. 1B, the spring 3, the pivot 2 and the upper and lower stoppers 4a and 4b are arranged with respect to the pedal key 1 from the player's side to the side away from the player. In this case, the spring 3 biases the pedal key 1 upward, and the pivot 2 is mounted on the pedal key 1. Referring to FIG. 1C, the upper stopper 4a, the spring 3, the pivot 2 and the lower stopper 4b are sequentially arranged with respect to the pedal key 1 from the player's side to the side away from the player. In this case, the spring 3 biases the pedal key upward and the pivot 2 is mounted on the pedal key 1. Referring to FIG. 1D, the upper and lower stoppers 4a and 4b, the pivot 2 and the spring 3 are sequentially arranged with respect to the pedal key 1 from the player's side to the side away from the player. In this case, the spring 3 biases the pedal key 1 downward, and the pivot 2 supports the pedal key 1 upward. In a structure shown in FIG. 1E, the upper stopper 4a, the pivot 2, the spring 3 and the lower stopper 4b are sequentially arranged with respect to the pedal key 1 from the player's side to the side away from the player. In this case, the spring 3 biases the pedal key 1 downward, and the pivot 2 supports the pedal key 1 thereon. Now assume that stop feeling of the pedal key is considered. In order to obtain good stop feeling, some distance should be provided between the pivot 2 and the lower stopper 4b. However, in cases wherein the spring 3 is located in front of the pivot 2 as shown in FIG. 1B, the upper stopper 4a is located in front of the pivot 2 as shown in FIGS. 1C and 1E, and the spring 3 is located behind the pivot 2 as shown in FIG. 1A, the depth of a frame 5 which forms a bottom portion of the instrument housing and on which the pedal keys are mounted becomes large in size, resulting in inconvenience.
In the structure of FIG. 1A wherein the spring 3 is located between the pivot 2 and the upper and lower stoppers 4a and 4b, the size of the frame 5 can be decreased. However, since the pedal keys 1 are arranged on the lower surface of the frame 5, the spring 3 must comprise a tension spring, or a spring seat member located under the pedal key 1 must be integrally formed with the frame and a compression coil spring must be inserted between the spring seat member and the pedal key 1. According to the former construction, hooks are provided at two ends of the tension spring and are hooked to the pedal key 1 and the frame 5. The assembly operation becomes complicated, and spring forces vary. As a result, uniform musical performance cannot be accomplished. According to the latter structure, since the spring seat member is required, the assembly operation of the member on the frame 5 results in high cost.